Antioxidants In Polypropylene Research Articles

Determination of Antioxidant Irganox 1010 in Polypropylene by Infrared Spectrometry

The content of antioxidant 1010 in polypropylene was quantitatively analyzed by infrared spectroscopy. After comparing the IR spectra of antioxidant 1010 and polypropylene, the characteristic absorption peak of antioxidant 1010 in polypropylene is determined to be 1744cm-1. The standard curve of antioxidant 1010 was drawn. The results show that there is a good linear relationship between the content of antioxidant 1010 and the absorption intensity of its characteristic peak, and the correlation coefficient is greater than 0.98. The content of antioxidant 1010 in the sample to be tested was determined by standard curve. The maximum relative error was 4%. Infrared spectroscopy can be used to analyze the content of antioxidant 1010 in polypropylene quickly and accurately. It is of great significance to study the migration of antioxidant in polypropylene and the quality control of products.

Synthesis of Polyethylene‐Grafted Phosphite Antioxidant and Its Antioxidant Behavior in Polypropylene

AbstractA novel macromolecular auxiliary antioxidant with polyethylene (PE) as polymer skeleton and phosphites as side groups is prepared based on commercial ethylene‐vinyl acetate (EVA) copolymers and its potential as polyolefin stabilizers is studied in depth. The synthesis approach of this PE‐grafted antioxidant consists of a typical EVA hydrolysis reaction and a two‐step nucleophilic substitution reaction of PCl3, 2,4‐di‐tert‐butylphenol, and the hydrolysis product. Results of the thermogravimetric analysis show that the macromolecular structures endow the as‐synthesized antioxidant with much better thermal stability than that of the commercial antioxidant 168. In addition, antioxidant behaviors of the PE‐grafted antioxidants in polypropylene (PP) matrix are investigated in detail through characterization of the melt flow index of multiple‐extruded stabilized PP as well as the short‐term oxidation induction time test and the long‐term thermo‐oxidative aging test. Results show that even with extremely low content of the effective antioxidant groups, the as‐synthesized macromolecular antioxidant still has excellent antioxygenic properties.

Accelerated laboratory weathering of polypropylene composites filled with synthetic silicon-based compounds

Non-functionalized and n-alkyl functionalized polyhedral oligomeric silsesquioxanes (POSS), siloxane-silsesquioxane resins and the sol-gel silicas were for the first time examined as possible UV-stabilizers and/or antioxidants in polypropylene (PP). The obtained composites were subjected to the accelerated laboratory weathering tests. The influence of the weathering conditions on the structure and properties of the PP materials was evaluated on the basis of the results from Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) studies. It was found that weathering resistance of the PP materials was strongly depended on the kind of the silicon-based filler used. Functionalized silsesquioxanes and siloxane-silsesquioxane resins improved weathering resistance of the PP materials, most probably because of its uniform dispersion in polymer, and thus, they could be considered as antioxidant additives. The changes in structural characteristics influenced thermal properties of the PP composites. It was revealed that the addition of the n-alkyl functionalized POSS and siloxane-silsesquioxane resins caused less significant changes in the melting and crystallization behaviour of PP materials.

Migration Study of Butylated Hydroxytoluene and Irganox 1010 from Polypropylene Treated with Severe Processing Conditions.

The antioxidants with hydrophobic nature such as butylated hydroxytoluene (BHT) and Irganox 1010 (I-1010) in polypropylene sheets would be migrated to foods, which is an important issue for industrial production food packaging materials. Migration behavior was promoted by severe processing conditions such as autoclave heating, microwave radiation, freezing, and especially autoclave heating treatment led the highest migration among them. Therefore, control of chemical additive migration from polypropylene food packaging is needed for safe food processing.

Facile synthesis of oligo(4‐methoxyphenol) in water and evaluation of its efficiency in stabilization of polypropylene

A hindered polyphenol, oligo(4‐methoxyphenol), has been first successfully synthesized via a mild biocatalytic pathway using horseradish peroxidase as catalyst in water without any additive. Then the efficiency of oligo(4‐methoxyphenol) in stabilization of polypropylene (PP) was evaluated in terms of thermal analysis and accelerated aging test. It was observed that the apparent activation energy for thermal decomposition of PP/oligo(4‐methoxyphenol) calculated by Friedman's method is higher than that of virgin PP. Oligo(4‐methoxyphenol)‐stabilized PP maintains its tensile strength even after aging at 120°C for 800 hours. Oxidation induction time and onset oxidation temperature of PP/oligo(4‐methoxyphenol) are higher than both virgin PP and PP/4‐methoxyphenol, as well as PP stabilized with commercially available 6‐di‐tert‐buty‐4‐methylphenol or 1076. These results indicate that oligo(4‐methoxyphenol) can effectively improve the thermo‐oxidative resistance of PP. Noting that oligo(4‐methoxyphenol) is synthesized via enzymatic polymerization in water under mild condition with a facile procedure, oligo(4‐methoxyphenol) is thus proposed as a new efficiency and readily available antioxidant for PP.

Selective aminolysis of acetylated lignin: Toward simultaneously improving thermal-oxidative stability and maintaining mechanical properties of polypropylene

Even with outstanding radical capturing ability, the utilization of lignin as a natural antioxidant in polypropylene (PP) still has been pended. Usually, the compatibility of its blends is improved based on the reaction of hydroxyl content, thus leading to the decreasing content of phenolic hydroxyl (Ph-OH) group and inferior thermal-oxidative stability of lignin blends. Here, the selective aminolysis of acetylated Kraft lignin (pyr-KL) was investigated, which structures were characterized using FTIR, 31P-NMR and GPC. The Ph-OH group of acetylated KL could be released by the addition of pyrrolidine; however the aliphatic hydroxyl group is still blocked. With the control of reaction conditions, the highest oxidation induction time of pyr-KL/PP (0.5wt% loading) reaches up to 22.6min, almost 2.6 times than that of pure PP. More importantly, the mechanical properties of PP were also maintained under the loading of pyr-KL, which is much better than that of curde KL/PP.

Relationship between bridged groups and antioxidant activity for aliphatic diamine bridged hindered phenol in polyolefins

ABSTRACTFour aliphatic diamine bridged hindered phenols were successfully synthesized with aliphatic diamine as the bridged group and 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionyl chloride as the material, and their structures were clarified by NMR, Fourier transform infrared spectroscopy, and mass spectrometry. Their performance as antioxidant for polypropylene (PP) and linear low‐density polyethylene (LLDPE) were investigated through the melt flow rate and the oxidation induction time. The thermooxidative stabilities of PP and LLDPE with different aliphatic diamine bridged hindered phenols were assessed by the measurement of the oxidation induction temperature and with long‐term aging testing. The results showed that aliphatic diamine bridged hindered phenols could protect two kinds of polyolefins from thermal oxidative degradation, and the mechanical properties and antioxidant activities of polyolefins stabilized with aliphatic diamine bridged hindered phenols were increased with increasing length of the bridged group for aliphatic diamine bridged hindered phenols at the same concentration of phenolic hydroxyl group. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45095.

Thermal-oxidative effect of a co-condensed nanosilica-based antioxidant in polypropylene

Antioxidant in form of hindered phenol structure is commonly used to prolong the service life of polymer, while the low molecule antioxidant has defect for its low thermal stability and physical loss. Herein, the feasibility of using co-condensed silica immobilized antioxidant (denoted as SN-NH2-AO) to improve the thermal-oxidative stability of polypropylene (PP) was evaluated. Firstly, SN-NH2-AO was prepared by immobilization of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid (AO) on the surface of co-condensed silica (SN-NH2) which was synthesized by co-hydrolysis and condensation of tetraethoxysilane and aminopropyltriethoxysilane. Compared with AO, SN-NH2-AO exhibited higher thermal stability. Further, SN-NH2-AO was incorporated into PP by melt blending. The incorporation of SN-NH2-AO could not only disperse well in PP matrix but also improve the thermal-oxidative stability of PP distinctly. It was found that although the anti-oxidative efficiency of SN-NH2-AO was slightly inferior to AO, SN-NH2-AO exhibited superiority on anti-extraction property.

Effect of Dihydromyricetin on the Stability of Polypropylene in Natural Weathering Tests

ABSTRACTEffects of dihydromyricetin (DMY), extracted from Ampelopsis grossedentata, on the antioxidantive properties of polypropylene were evaluated by investigating differences in mechanical properties and melt flowability between pre- and post-natural weathering tests. For comparison purposes, the effects of a synthetic phenolic commercial antioxidant (Irganox 1010) were also analyzed. The results showed that reduction in mechanical properties and increment in melt flowability of polypropylene containing DMY were slower than that of unstabilized reference during the aging process, which implies that DMY exhibits high efficiency as a thermal antioxidant for polypropylene. On the other hand, samples that contained Irganox 1010 obtained further improved stability over the samples containing DMY during 105 days; however, the effectiveness of DMY lasted longer than that of Irganox 1010. DMY has a characteristic of being harmless and having high activity, good stability, and abundant resources to be a good natural antioxidant.

Enzymatic synthesis of polyguaiacol and its thermal antioxidant behavior in polypropylene

Polyguaiacol was successfully synthesized by enzyme-catalyzed polymerization in an aqueous micelle system with horseradish peroxidase (HRP) as the catalyst. As-synthesized polyguaiacol was characterized by infrared spectrometry and gel permeation chromatography, and its thermal stability was evaluated by thermogravimetric analysis. Besides, the thermal antioxidant behavior of the as-synthesized phenolic polymer as an antioxidant in polypropylene was evaluated by differential scanning calorimetry and accelerated aging test, and the apparent activation energies of thermal decomposition of polypropylene (PP) were calculated by Friedman method. Results show that the as-synthesized polyguaiacol as an antioxidant is able to significantly increase the oxidation induction time of virgin PP, and it exhibits better antioxidative performance than corresponding monomer. Moreover, polyguaiacol, the as-synthesized phenolic polymer, exhibits good resistance against aging of polypropylene.

Synergistic effect of phosphite with fullerene C60 and fullerenol C60(OH)24 as antioxidants in polypropylene

Polypropylene samples with fullerene C60, fullerenol C60(OH)24, 1010, C60/168, C60-OH/168 and 1010/168 as antioxidants were prepared by extrusions. MFR, YI, TGA and OIT of all the samples were tested. According to the results of MFR, during the melt extrusion, fullerene showed excellent stability effect on PP. The antioxidative ability of fullerene was comparable to the traditional antioxidant 1010. The antioxidative ability of fullerenol was not significant in the first extrusion and it accelerated the degradation of PP in the second and the third extrusions. TGA and OIT tests showed that the stability effects of fullerene and fullerenol were slightly lower than antioxidant 1010. In the first time, antioxidant 168 was reported to show great synergistic effects with fullerene and fullerenol as antioxidants, which sussested a simple way to enhance the antioxidative abilities of fullerene and fullerenol.

Synthesis, characterization, and application of a hydrolytically stable liquid phosphite

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by negatively affecting the kinetics. In particular, liquid phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers, but they are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in liquid phosphites, a novel hydrolytically stable liquid phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:163–168, 2016. © 2014 Society of Plastics Engineers

Synthesis, characterization, and application of oligomer‐type‐based phosphites

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by affecting the kinetics. In particular, oligomer‐type phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers. Generally, phosphites are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in phosphites, a novel hydrolytically stable oligomeric phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:146–155, 2016. © 2014 Society of Plastics Engineers

An approach to assess the synergistic effect of natural antioxidants on the performance of the polypropylene stabilizing systems

AbstractA study on the efficiency of natural antioxidants from agri‐food industry wastes as long‐term antioxidants for polypropylene (PP) is reported. Special attention is paid to the usage of vegetal wastes as a source of natural antioxidants such as alternatives to synthetic long‐term antioxidants. The potential of the lignin‐derived fractions generated during autoydrolysis processing of lignocellulosic agricultural, forestal, and food wastes was assessed. The measurements of oxidation induction time were used for obtaining information on long‐term antioxidant effectiveness, showing the protective effect of natural extracts. The protective effect was improved in combinations of natural extracts with 0.1% and 0.2% of Irgafos 168 (short‐term antioxidant) besides a synergistic effect was exhibited when 0.4% of Irgafos 168 is added. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Dissolution Behaviour of the Antioxidant in Polypropylene in Tap Water and Evaluation of the Polymer Degradation

Dissolution Behaviour of the Antioxidant in Polypropylene in Tap Water and Evaluation of the Polymer Degradation

Thermal Oxidation Behaviour and Degradation Kinetics of Polypropylene with p-tert-Butylcalix[n]arenes

p-tert-butylcalix[4]arene (C4), p-tert-butylcalix [6]arene (C6) and p-tert-butylcalix[8]arene (C8) were synthesized and explored as antioxidants for polypropylene (PP). The structures of these compounds were characterized by 1H-NMR and FTIR, and their antioxidation efficiencies for PP were evaluated by rheology analysis, differential scanning calorimetry (DSC), melt flow index analysis, and thermogravimetric analysis (TGA). The rheology results from a Haake Polydrive mixer revealed that calix[n]arenes had little effect in preventing PP from degradation during the processing, and the DSC analysis showed that the antioxidation performance of the calix[n]arenes for PP was in the order of C4 > C6> C8. The values of melt flow index indicated that calix[n]arenes, especially C4 and C6, could largely improve the thermal stability of PP, and the activation energies for degradation of PP with C4, C6 and C8 calculated with the data from TGA were 97.05, 84.60 and 53.69 kJ/mol, respectively.

Synthesis of 3,5-ditert-butyl-4-hydroxybenzoates and their thermal antioxidation behavior for polypropylene

Butyl 3,5-ditert-butyl-4-hydroxybenzoate (BB), octyl 3,5-ditert-butyl-4-hydroxybenzoate (OB), and dodecyl 3,5-ditert-butyl-4-hydroxybenzoate (DB) were synthesized and characterized, and their performance as antioxidant for polypropylene (PP) were also investigated. The thermooxidative stability of PP with different antioxidants were assessed by the measurements of long-term accelerated aging, differential scanning calorimetery, and thermogravimetric analysis. The results showed that 3,5-ditert-butyl-4-hydroxybenzoates could effectively inhibit the oxidation degradation of PP. And it was also found that the antioxidant efficiency of BB, OB, and DB for PP was in the order of DB > OB > BB.

Effect of secondary structure on physical behaviour and performance of hindered phenolic antioxidants in polypropylene

The performances of five hindered phenolic antioxidants of molecular weights between 206 and 1178, all containing 2,6-di-tert-butylphenol functionalities (I), were studied from the view-point of long-term heat ageing (LTHA) and processing stabilities in isotactic polypropylene. In order to separate the chemical effect from physical interactions with the matrix, efficiencies of stabilizers were studied in equimolar 0.1% concentrations of (I) in the polymer. Under such conditions, the chemical reactions of all the compounds were expected to be equal and all the differences in performances were accounted for purely by the physical interactions between stabilizer and polymer. In the solid semi-crystalline polymer, the effect of physical loss was intense so far, that at molecular weights below 300–400 in LTHA tests at 130 and 150 °C, performances of stabilizers were considerably diminished. On the other hand, in processing tests, the contribution of secondary structure was found to be practically meaningless and the performances of stabilizers tested were controlled almost exclusively by the chemistry of the active moiety (I).

Some features of phenolic inhibitor consumption in oxidized polypropylene in the presence of synergists–hydroperoxide decomposers

AbstractThe influence of sulfur and phosphors containing substances, hydroperoxide decomposers, on the kinetics of the consumption of two phenolic antioxidants in polypropylene (PP) was studied. The induction periods of PP autoxidation at 130°C were measured in the presence of inhibiting compositions that consisted of phenolic inhibitors and decomposers of hydroperoxide. The obtained results indicated that the influence of the hydroperoxide decomposer became significant when the concentration of the phenolic antioxidant became close to a critical value. It was shown also that the influence of the hydroperoxide decomposer significantly depended on the mechanism of the phenolic inhibitor transformation: first of all, on the nature of its transformation products. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2226–2229, 2003

Influence of synergists: The influence of hydroperoxide decomposers on phenolic inhibitors consumption in oxidized polypropylene

AbstractThe influence of sulphur‐ and phosphorum‐containing substances (hydroperoxide decomposers) on the kinetics of the consumption of two phenolic antioxidants in polypropylene (PP) was studied. The induction periods of PP autoxidation at 130°C were measured in the presence of inhibiting compositions that consisted of phenolic inhibitors and decomposers of hydroperoxide. Obtained results indicated that the influence of the hydroperoxide decomposer became significant when the concentration of the phenolic antioxidant became close to critical value. It also was shown that the efficiency of the hydroperoxide decomposer significantly depended on the mechanism of the transformation of the phenolic inhibitor; and first of all on the nature of its transformation products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2239–2243, 2002